Seasonal changes in the oviduct of the pied myna (Aves: Sturnidae)

Study of the oviduct of the pied myna (Sturnus contra contra) throughout the year reveals that oviductal weight, length, surface epithelial height and glycogen content are low during August to January (nonbreeding phase), partially increase during February to April (pre-breeding phase), maximally increase in May (breeding phase) and decrease in June and July (post-breeding phase). In the nesting cycle, there is greatest growth in all the regions of the oviduct from early nest-building to the egg-laying period and this is followed by rapid involution during incubation and nestling periods. Some notable features in the oviduct of the pied myna are described: 1) All five regions of the oviduct (infundibulum, magnum, isthmus, uterus, and vagina) are clearly distinguishable when studied from serial sections of the oviduct even during the nonbreeding phase of the annual ovarian cycle. 2) There is a strong correlation between initiation of tubular gland formation and the onset of nestbuilding activity. 3) The distal part of the magnum is differentiated into a 'mucous region' having well developed basal nonciliated cells. 4) A sixth zone can be identified between the magnum and isthmus. Sperm hostlike glands exist at the cranial end of the zone. 5) Several circular epithelial invaginations are evident in the intermucosal folds and their size decreases in centripetal order in the vagina. 6) The pattern and degree of regression are different in various regions of the oviduct. A close synchrony between ovarian and oviducal cycles is indicated in the pied myna (Sturnus contra contra).     

Reproductive performance of four aphidophagous ladybirds on cowpea aphid, Aphis craccivora Koch

Abstract:  This study investigated prey consumption, egg production, percent progeny loss, reproductive, pre- and post-reproductive periods, reproductive time ratio, reproductive rate and bioconversion efficiency of four aphidophagous ladybirds, viz. Cheilomenes sexmaculata (Fabricius), Coccinella septempunctata Linnaeus, Coccinella transversalis Fabricius and Propylea dissecta (Mulsant) on Dolichos lablab Linnaeus infested with cowpea aphid, Aphis craccivora Koch. C. sexmaculata had the highest bioconversion efficiency, reproductive rate and reproductive time ratio followed in rank order by P. dissecta , C. transversalis and C. septempunctata . This study indicates that C. sexmaculata has a narrow ecological relationship with A. craccivora . The increased allocation of resources to reproduction as indicated through a high reproductive time ratio and high bioconversion efficiency of C. sexmaculata and P. dissecta suggest that they may be better adapted to compete for this prey with larger species like C. transversalis and C. septempunctata .     

A simple and sensitive spectrophotometric method for the quantitative determination of solid supported amino groups

A simple and sensitive method for the quantitative determination of free amino groups on solid support is described. This approach is a modification of Ngo's [(1986) J. Biochem. Biophys. Methods 12, 349-354] method reported earlier. The method is based on the reaction of the solid support with an excess of 5'-O-(4,4'-dimethoxytrityl)-thymidine-3'-O-(2,4-dinitrophenyl) succinate (DTDS) in the presence of a catalytic amount of 4-dimethylaminopyridine. After removing the excess reagent, solid support is treated with perchloric acid to release 4,4'-dimethoxytrityl cation into the solution. The released 4,4'-dimethoxytrityl cation, which has a strong absorption at 498 nm (epsilon 498 = 70,000), is then determined spectrophotometrically. A comparative study of DTDS, N-succinimidyl-3-(2-pyridyldithio)propionate and 4,4-dimethoxytrityl chloride is also included. The method was found to be very useful to determine those amino groups which are available for functionalization of solid supports, especially, monitoring the functionalization of solid supports for affinity chromatography and synthesis of biopolymers.     

Role of central histaminergic mechanism in behavioural depression (swimming despair) in mice

The role of the central histaminergic system in depression was studied by using swimming despair test in mice - a behavioural model of depression. In this test, immobility of mice reflects a state of depression. Intracerebral (ic) injection of histamine (50-200 micrograms) increased significantly the immobility. The H1-receptor blocker mepyramine (2.5-20 mg/kg ip) had no effect while H2-receptor blocker cimetidine (100-200 micrograms ic) caused a significant decrease in immobility. The histamine induced facilitation was blocked completely by cimetidine and antidepressant drugs-imipramine and desipramine, but remained unaffected in mice pretreated with mepyramine or atropine. The H2 agonist impromidine (20-40 micrograms ic) also enhanced significantly, the immobility which was blocked by cimetidine and antidepressant drugs. It has been concluded that central H2-receptors facilitate depression and antidepressant drugs block central H2-receptors.